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	$193.80	3.562%	$200.7032	$200.70	$200.70	$200.70
Purchase #2	$97.94	13.834%	$111.489	$111.49	$111.50	$111.50
Purchase #3	$197.74	7.611%	$212.79	$212.79	$212.80	$212.80
Purchase #4	$222.97	5.680%	$235.6347	$235.63	$235.65	$235.60
Purchase #5	$99.58	11.810%	$111.3404	$111.34	$111.35	$111.30
Purchase #6	$117.89	3.735%	$122.2932	$122.29	$122.30	$122.30
Purchase #7	$43.61	11.290%	$48.5336	$48.53	$48.55	$48.50
7 purchase totals =	$973.53		$1,042.7841	$1,042.77	$1,042.85	$1,042.70