Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$196.50	13.522%	$223.0707	$223.07	$223.05	$223.10
Purchase #2	$233.72	10.781%	$258.9174	$258.92	$258.90	$258.90
Purchase #3	$249.54	10.186%	$274.9581	$274.96	$274.95	$275.00
Purchase #4	$90.89	8.317%	$98.4493	$98.45	$98.45	$98.40
Purchase #5	$48.45	4.694%	$50.7242	$50.72	$50.70	$50.70
Purchase #6	$138.47	13.399%	$157.0236	$157.02	$157.00	$157.00
Purchase #7	$119.33	4.861%	$125.1306	$125.13	$125.15	$125.10
7 purchase totals =	$1,076.90		$1,188.2739	$1,188.27	$1,188.20	$1,188.20