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	$223.39	10.667%	$247.219	$247.22	$247.20	$247.20
Purchase #2	$40.26	10.666%	$44.5541	$44.55	$44.55	$44.60
Purchase #3	$161.46	4.433%	$168.6175	$168.62	$168.60	$168.60
Purchase #4	$53.58	11.211%	$59.5869	$59.59	$59.60	$59.60
Purchase #5	$247.71	3.515%	$256.417	$256.42	$256.40	$256.40
Purchase #6	$16.44	6.709%	$17.543	$17.54	$17.55	$17.50
Purchase #7	$210.91	10.263%	$232.5557	$232.56	$232.55	$232.60
7 purchase totals =	$953.75		$1,026.4932	$1,026.50	$1,026.45	$1,026.50