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	$232.55	9.417%	$254.4492	$254.45	$254.45	$254.40
Purchase #2	$193.33	13.738%	$219.8897	$219.89	$219.90	$219.90
Purchase #3	$36.57	13.262%	$41.4199	$41.42	$41.40	$41.40
Purchase #4	$238.94	7.302%	$256.3874	$256.39	$256.40	$256.40
Purchase #5	$39.77	10.141%	$43.8031	$43.80	$43.80	$43.80
Purchase #6	$218.28	5.745%	$230.8202	$230.82	$230.80	$230.80
Purchase #7	$53.72	11.343%	$59.8135	$59.81	$59.80	$59.80
7 purchase totals =	$1,013.16		$1,106.5830	$1,106.58	$1,106.55	$1,106.50