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	$196.50	13.562%	$223.1493	$223.15	$223.15	$223.10
Purchase #2	$147.72	5.419%	$155.7249	$155.72	$155.70	$155.70
Purchase #3	$216.91	5.476%	$228.788	$228.79	$228.80	$228.80
Purchase #4	$99.72	11.833%	$111.5199	$111.52	$111.50	$111.50
Purchase #5	$186.77	8.167%	$202.0235	$202.02	$202.00	$202.00
Purchase #6	$233.72	13.833%	$266.0505	$266.05	$266.05	$266.10
Purchase #7	$31.82	8.346%	$34.4757	$34.48	$34.50	$34.50
7 purchase totals =	$1,113.16		$1,221.7318	$1,221.73	$1,221.70	$1,221.70