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	$119.61	10.504%	$132.1738	$132.17	$132.15	$132.20
Purchase #2	$43.53	3.156%	$44.9038	$44.90	$44.90	$44.90
Purchase #3	$89.86	3.199%	$92.7346	$92.73	$92.75	$92.70
Purchase #4	$244.89	7.852%	$264.1188	$264.12	$264.10	$264.10
Purchase #5	$179.54	10.859%	$199.0362	$199.04	$199.05	$199.00
Purchase #6	$139.52	10.457%	$154.1096	$154.11	$154.10	$154.10
Purchase #7	$140.51	13.543%	$159.5393	$159.54	$159.55	$159.50
7 purchase totals =	$957.46		$1,046.6161	$1,046.61	$1,046.60	$1,046.50