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	$212.66	13.651%	$241.6902	$241.69	$241.70	$241.70
Purchase #2	$204.70	12.717%	$230.7317	$230.73	$230.75	$230.70
Purchase #3	$36.76	9.531%	$40.2636	$40.26	$40.25	$40.30
Purchase #4	$50.84	7.152%	$54.4761	$54.48	$54.50	$54.50
Purchase #5	$68.74	5.834%	$72.7503	$72.75	$72.75	$72.80
Purchase #6	$193.54	13.595%	$219.8518	$219.85	$219.85	$219.90
Purchase #7	$59.54	11.594%	$66.4431	$66.44	$66.45	$66.40
7 purchase totals =	$826.78		$926.2068	$926.20	$926.25	$926.30