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	$232.35	4.465%	$242.7244	$242.72	$242.70	$242.70
Purchase #2	$214.34	6.818%	$228.9537	$228.95	$228.95	$229.00
Purchase #3	$219.48	4.777%	$229.9646	$229.96	$229.95	$230.00
Purchase #4	$83.80	10.144%	$92.3007	$92.30	$92.30	$92.30
Purchase #5	$53.44	3.422%	$55.2687	$55.27	$55.25	$55.30
Purchase #6	$26.52	6.802%	$28.3239	$28.32	$28.30	$28.30
Purchase #7	$242.43	3.313%	$250.4617	$250.46	$250.45	$250.50
7 purchase totals =	$1,072.36		$1,127.9977	$1,127.98	$1,127.90	$1,128.10