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	$190.95	3.820%	$198.2443	$198.24	$198.25	$198.20
Purchase #2	$37.58	3.541%	$38.9107	$38.91	$38.90	$38.90
Purchase #3	$77.80	6.434%	$82.8057	$82.81	$82.80	$82.80
Purchase #4	$66.64	7.276%	$71.4887	$71.49	$71.50	$71.50
Purchase #5	$209.80	6.627%	$223.7034	$223.70	$223.70	$223.70
Purchase #6	$220.39	3.379%	$227.837	$227.84	$227.85	$227.80
Purchase #7	$233.53	11.479%	$260.3369	$260.34	$260.35	$260.30
7 purchase totals =	$1,036.69		$1,103.3267	$1,103.33	$1,103.35	$1,103.20