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	$166.33	4.680%	$174.1142	$174.11	$174.10	$174.10
Purchase #2	$205.77	8.203%	$222.6493	$222.65	$222.65	$222.60
Purchase #3	$232.47	8.355%	$251.8929	$251.89	$251.90	$251.90
Purchase #4	$84.73	12.297%	$95.1492	$95.15	$95.15	$95.10
Purchase #5	$202.68	6.679%	$216.217	$216.22	$216.20	$216.20
Purchase #6	$59.41	8.809%	$64.6434	$64.64	$64.65	$64.60
Purchase #7	$57.73	7.119%	$61.8398	$61.84	$61.85	$61.80
7 purchase totals =	$1,009.12		$1,086.5058	$1,086.50	$1,086.50	$1,086.30