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	$116.57	11.520%	$129.9989	$130.00	$130.00	$130.00
Purchase #2	$16.81	6.482%	$17.8996	$17.90	$17.90	$17.90
Purchase #3	$111.45	6.146%	$118.2997	$118.30	$118.30	$118.30
Purchase #4	$137.45	11.119%	$152.7331	$152.73	$152.75	$152.70
Purchase #5	$52.33	7.428%	$56.2171	$56.22	$56.20	$56.20
Purchase #6	$83.39	7.207%	$89.3999	$89.40	$89.40	$89.40
Purchase #7	$155.81	8.428%	$168.9417	$168.94	$168.95	$168.90
7 purchase totals =	$673.81		$733.4900	$733.49	$733.50	$733.40