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	$30.72	7.625%	$33.0624	$33.06	$33.05	$33.10
Purchase #2	$188.35	4.328%	$196.5018	$196.50	$196.50	$196.50
Purchase #3	$220.56	4.504%	$230.494	$230.49	$230.50	$230.50
Purchase #4	$35.39	11.738%	$39.5441	$39.54	$39.55	$39.50
Purchase #5	$152.27	4.630%	$159.3201	$159.32	$159.30	$159.30
Purchase #6	$247.32	3.381%	$255.6819	$255.68	$255.70	$255.70
Purchase #7	$219.56	11.267%	$244.2978	$244.30	$244.30	$244.30
7 purchase totals =	$1,094.17		$1,158.9021	$1,158.89	$1,158.90	$1,158.90