fix problem with price not rounding up right

Author: senadir

assets/js/blocks/price-filter/constants.js

@@ -0,0 +1,2 @@
+export const ROUND_UP = 'ROUND_UP';
+export const ROUND_DOWN = 'ROUND_DOWN';

assets/js/blocks/price-filter/use-price-constraints.js

@@ -3,10 +3,31 @@
  */
 import { usePrevious } from '@woocommerce/base-hooks';
 
-export const usePriceConstraint = ( price ) => {
-	const currentConstraint = isNaN( price )
-		? null
-		: Math.floor( parseInt( price, 10 ) / 10 ) * 10;
+/**
+ * Internal dependencies
+ */
+import { ROUND_UP, ROUND_DOWN } from './constants';
+
+/**
+ * Return the price constraint.
+ *
+ * @param {number} price Price in minor unit, e.g. cents.
+ * @param {number} minorUnit Price minor unit (number of digits after the decimal separator).
+ * @param {ROUND_UP|ROUND_DOWN} direction Rounding flag whether we round up or down.
+ */
+export const usePriceConstraint = ( price, minorUnit, direction ) => {
+	const step = 10 * 10 ** minorUnit;
+	let currentConstraint;
+	if ( direction === ROUND_UP ) {
+		currentConstraint = isNaN( price )
+			? null
+			: Math.ceil( parseFloat( price, 10 ) / step ) * step;
+	} else if ( direction === ROUND_DOWN ) {
+		currentConstraint = isNaN( price )
+			? null
+			: Math.floor( parseFloat( price, 10 ) / step ) * step;
+	}
+
 	const previousConstraint = usePrevious( currentConstraint, ( val ) =>
 		Number.isFinite( val )
 	);
@@ -15,9 +36,9 @@ export const usePriceConstraint = ( price ) => {
 		: previousConstraint;
 };
 
-export default ( { minPrice, maxPrice } ) => {
+export default ( { minPrice, maxPrice, minorUnit } ) => {
 	return {
-		minConstraint: usePriceConstraint( minPrice ),
-		maxConstraint: usePriceConstraint( maxPrice ),
+		minConstraint: usePriceConstraint( minPrice, minorUnit, ROUND_DOWN ),
+		maxConstraint: usePriceConstraint( maxPrice, minorUnit, ROUND_UP ),
 	};
 };