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	$202.73	10.275%	$223.5605	$223.56	$223.55	$223.60
Purchase #2	$147.51	3.650%	$152.8941	$152.89	$152.90	$152.90
Purchase #3	$30.93	4.463%	$32.3104	$32.31	$32.30	$32.30
Purchase #4	$149.37	7.301%	$160.2755	$160.28	$160.30	$160.30
Purchase #5	$20.69	7.139%	$22.1671	$22.17	$22.15	$22.20
Purchase #6	$230.70	9.196%	$251.9152	$251.92	$251.90	$251.90
Purchase #7	$163.83	11.117%	$182.043	$182.04	$182.05	$182.00
7 purchase totals =	$945.76		$1,025.1658	$1,025.17	$1,025.15	$1,025.20