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	$111.96	12.482%	$125.9348	$125.93	$125.95	$125.90
Purchase #2	$18.49	11.677%	$20.6491	$20.65	$20.65	$20.60
Purchase #3	$31.41	5.275%	$33.0669	$33.07	$33.05	$33.10
Purchase #4	$67.76	5.610%	$71.5613	$71.56	$71.55	$71.60
Purchase #5	$101.35	10.248%	$111.7363	$111.74	$111.75	$111.70
Purchase #6	$175.85	11.449%	$195.9831	$195.98	$196.00	$196.00
Purchase #7	$199.60	8.539%	$216.6438	$216.64	$216.65	$216.60
7 purchase totals =	$706.42		$775.5753	$775.57	$775.60	$775.50