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	$196.85	9.354%	$215.2633	$215.26	$215.25	$215.30
Purchase #2	$137.84	5.503%	$145.4253	$145.43	$145.45	$145.40
Purchase #3	$247.68	6.363%	$263.4399	$263.44	$263.45	$263.40
Purchase #4	$197.89	11.769%	$221.1797	$221.18	$221.20	$221.20
Purchase #5	$41.84	8.187%	$45.2654	$45.27	$45.25	$45.30
Purchase #6	$133.76	5.319%	$140.8747	$140.87	$140.85	$140.90
Purchase #7	$29.48	13.717%	$33.5238	$33.52	$33.50	$33.50
7 purchase totals =	$985.34		$1,064.9721	$1,064.97	$1,064.95	$1,065.00