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	$59.28	4.428%	$61.9049	$61.90	$61.90	$61.90
Purchase #2	$17.31	8.748%	$18.8243	$18.82	$18.80	$18.80
Purchase #3	$239.48	10.560%	$264.7691	$264.77	$264.75	$264.80
Purchase #4	$215.39	3.512%	$222.9545	$222.95	$222.95	$223.00
Purchase #5	$196.59	8.109%	$212.5315	$212.53	$212.55	$212.50
Purchase #6	$247.30	5.732%	$261.4752	$261.48	$261.50	$261.50
Purchase #7	$76.94	12.175%	$86.3074	$86.31	$86.30	$86.30
7 purchase totals =	$1,052.29		$1,128.7669	$1,128.76	$1,128.75	$1,128.80