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	$83.28	12.356%	$93.5701	$93.57	$93.55	$93.60
Purchase #2	$94.98	8.565%	$103.115	$103.12	$103.10	$103.10
Purchase #3	$135.51	12.181%	$152.0165	$152.02	$152.00	$152.00
Purchase #4	$224.41	8.855%	$244.2815	$244.28	$244.30	$244.30
Purchase #5	$100.89	10.663%	$111.6479	$111.65	$111.65	$111.60
Purchase #6	$145.94	13.540%	$165.7003	$165.70	$165.70	$165.70
Purchase #7	$221.84	7.222%	$237.8613	$237.86	$237.85	$237.90
7 purchase totals =	$1,006.85		$1,108.1926	$1,108.20	$1,108.15	$1,108.20