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	$86.83	6.664%	$92.6164	$92.62	$92.60	$92.60
Purchase #2	$223.74	8.590%	$242.9593	$242.96	$242.95	$243.00
Purchase #3	$85.29	8.520%	$92.5567	$92.56	$92.55	$92.60
Purchase #4	$214.31	11.392%	$238.7242	$238.72	$238.70	$238.70
Purchase #5	$67.72	13.331%	$76.7478	$76.75	$76.75	$76.70
Purchase #6	$244.71	13.254%	$277.1439	$277.14	$277.15	$277.10
Purchase #7	$37.72	4.251%	$39.3235	$39.32	$39.30	$39.30
7 purchase totals =	$960.32		$1,060.0718	$1,060.07	$1,060.00	$1,060.00