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	$176.26	3.188%	$181.8792	$181.88	$181.90	$181.90
Purchase #2	$9.70	12.198%	$10.8832	$10.88	$10.90	$10.90
Purchase #3	$95.43	10.193%	$105.1572	$105.16	$105.15	$105.20
Purchase #4	$159.51	7.627%	$171.6758	$171.68	$171.70	$171.70
Purchase #5	$46.44	13.561%	$52.7377	$52.74	$52.75	$52.70
Purchase #6	$110.56	9.323%	$120.8675	$120.87	$120.85	$120.90
Purchase #7	$83.47	7.651%	$89.8563	$89.86	$89.85	$89.90
7 purchase totals =	$681.37		$733.0569	$733.07	$733.10	$733.20