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	$201.90	12.117%	$226.3642	$226.36	$226.35	$226.40
Purchase #2	$238.51	6.725%	$254.5498	$254.55	$254.55	$254.50
Purchase #3	$85.82	7.122%	$91.9321	$91.93	$91.95	$91.90
Purchase #4	$98.64	12.830%	$111.2955	$111.30	$111.30	$111.30
Purchase #5	$46.76	3.358%	$48.3302	$48.33	$48.35	$48.30
Purchase #6	$60.89	12.211%	$68.3253	$68.33	$68.35	$68.30
Purchase #7	$231.81	5.760%	$245.1623	$245.16	$245.15	$245.20
7 purchase totals =	$964.33		$1,045.9594	$1,045.96	$1,046.00	$1,045.90