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	$196.47	11.833%	$219.7183	$219.72	$219.70	$219.70
Purchase #2	$57.53	5.403%	$60.6383	$60.64	$60.65	$60.60
Purchase #3	$40.90	3.548%	$42.3511	$42.35	$42.35	$42.40
Purchase #4	$124.86	6.305%	$132.7324	$132.73	$132.75	$132.70
Purchase #5	$165.77	12.130%	$185.8779	$185.88	$185.90	$185.90
Purchase #6	$32.79	13.297%	$37.1501	$37.15	$37.15	$37.20
Purchase #7	$70.29	6.370%	$74.7675	$74.77	$74.75	$74.80
7 purchase totals =	$688.61		$753.2356	$753.24	$753.25	$753.30