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	$176.46	10.529%	$195.0395	$195.04	$195.05	$195.00
Purchase #2	$139.47	9.827%	$153.1757	$153.18	$153.20	$153.20
Purchase #3	$61.91	13.243%	$70.1087	$70.11	$70.10	$70.10
Purchase #4	$10.91	5.639%	$11.5252	$11.53	$11.55	$11.50
Purchase #5	$132.52	9.839%	$145.5586	$145.56	$145.55	$145.60
Purchase #6	$247.65	3.435%	$256.1568	$256.16	$256.15	$256.20
Purchase #7	$200.47	11.221%	$222.9647	$222.96	$222.95	$223.00
7 purchase totals =	$969.39		$1,054.5292	$1,054.54	$1,054.55	$1,054.60