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	$145.35	4.678%	$152.1495	$152.15	$152.15	$152.10
Purchase #2	$124.25	4.716%	$130.1096	$130.11	$130.10	$130.10
Purchase #3	$140.31	7.316%	$150.5751	$150.58	$150.60	$150.60
Purchase #4	$52.66	7.697%	$56.7132	$56.71	$56.70	$56.70
Purchase #5	$244.51	11.721%	$273.169	$273.17	$273.15	$273.20
Purchase #6	$50.91	6.580%	$54.2599	$54.26	$54.25	$54.30
Purchase #7	$9.79	7.263%	$10.501	$10.50	$10.50	$10.50
7 purchase totals =	$767.78		$827.4773	$827.48	$827.45	$827.50