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	$221.38	10.630%	$244.9127	$244.91	$244.90	$244.90
Purchase #2	$115.95	6.627%	$123.634	$123.63	$123.65	$123.60
Purchase #3	$230.82	12.779%	$260.3165	$260.32	$260.30	$260.30
Purchase #4	$57.44	6.561%	$61.2086	$61.21	$61.20	$61.20
Purchase #5	$205.81	8.664%	$223.6414	$223.64	$223.65	$223.60
Purchase #6	$59.67	10.334%	$65.8363	$65.84	$65.85	$65.80
Purchase #7	$33.43	5.165%	$35.1567	$35.16	$35.15	$35.20
7 purchase totals =	$924.50		$1,014.7062	$1,014.71	$1,014.70	$1,014.60