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	$172.94	13.237%	$195.8321	$195.83	$195.85	$195.80
Purchase #2	$103.37	12.597%	$116.3915	$116.39	$116.40	$116.40
Purchase #3	$48.25	4.112%	$50.234	$50.23	$50.25	$50.20
Purchase #4	$223.76	4.240%	$233.2474	$233.25	$233.25	$233.20
Purchase #5	$174.54	12.753%	$196.7991	$196.80	$196.80	$196.80
Purchase #6	$160.93	3.220%	$166.1119	$166.11	$166.10	$166.10
Purchase #7	$200.90	5.102%	$211.1499	$211.15	$211.15	$211.10
7 purchase totals =	$1,084.69		$1,169.7659	$1,169.76	$1,169.80	$1,169.60