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	$211.65	7.361%	$227.2296	$227.23	$227.25	$227.20
Purchase #2	$78.50	8.478%	$85.1552	$85.16	$85.15	$85.20
Purchase #3	$240.95	7.591%	$259.2405	$259.24	$259.25	$259.20
Purchase #4	$59.75	7.774%	$64.395	$64.40	$64.40	$64.40
Purchase #5	$72.34	5.496%	$76.3158	$76.32	$76.30	$76.30
Purchase #6	$165.34	6.190%	$175.5745	$175.57	$175.55	$175.60
Purchase #7	$68.91	13.847%	$78.452	$78.45	$78.45	$78.50
7 purchase totals =	$897.44		$966.3626	$966.37	$966.35	$966.40