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	$41.52	11.513%	$46.3002	$46.30	$46.30	$46.30
Purchase #2	$9.35	12.615%	$10.5295	$10.53	$10.55	$10.50
Purchase #3	$193.48	6.551%	$206.1549	$206.15	$206.15	$206.20
Purchase #4	$232.27	5.248%	$244.4595	$244.46	$244.45	$244.50
Purchase #5	$78.71	13.852%	$89.6129	$89.61	$89.60	$89.60
Purchase #6	$92.73	6.502%	$98.7593	$98.76	$98.75	$98.80
Purchase #7	$201.86	10.830%	$223.7214	$223.72	$223.70	$223.70
7 purchase totals =	$849.92		$919.5377	$919.53	$919.50	$919.60