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	$168.88	9.141%	$184.3173	$184.32	$184.30	$184.30
Purchase #2	$66.98	10.221%	$73.826	$73.83	$73.85	$73.80
Purchase #3	$143.33	8.331%	$155.2708	$155.27	$155.25	$155.30
Purchase #4	$193.67	11.701%	$216.3313	$216.33	$216.35	$216.30
Purchase #5	$223.29	13.829%	$254.1688	$254.17	$254.15	$254.20
Purchase #6	$58.47	4.820%	$61.2883	$61.29	$61.30	$61.30
Purchase #7	$105.65	12.152%	$118.4886	$118.49	$118.50	$118.50
7 purchase totals =	$960.27		$1,063.6911	$1,063.70	$1,063.70	$1,063.70