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	$175.81	13.580%	$199.685	$199.69	$199.70	$199.70
Purchase #2	$7.36	5.489%	$7.764	$7.76	$7.75	$7.80
Purchase #3	$53.32	12.272%	$59.8634	$59.86	$59.85	$59.90
Purchase #4	$221.45	6.504%	$235.8531	$235.85	$235.85	$235.90
Purchase #5	$80.45	13.388%	$91.2206	$91.22	$91.20	$91.20
Purchase #6	$34.43	8.808%	$37.4626	$37.46	$37.45	$37.50
Purchase #7	$94.29	9.528%	$103.274	$103.27	$103.25	$103.30
7 purchase totals =	$667.11		$735.1227	$735.11	$735.05	$735.30