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	$224.55	4.684%	$235.0679	$235.07	$235.05	$235.10
Purchase #2	$225.82	13.415%	$256.1138	$256.11	$256.10	$256.10
Purchase #3	$140.63	8.629%	$152.765	$152.77	$152.75	$152.80
Purchase #4	$145.77	5.836%	$154.2771	$154.28	$154.30	$154.30
Purchase #5	$35.62	13.483%	$40.4226	$40.42	$40.40	$40.40
Purchase #6	$137.49	13.220%	$155.6662	$155.67	$155.65	$155.70
Purchase #7	$82.37	10.784%	$91.2528	$91.25	$91.25	$91.30
7 purchase totals =	$992.25		$1,085.5654	$1,085.57	$1,085.50	$1,085.70