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	$192.73	3.848%	$200.1463	$200.15	$200.15	$200.10
Purchase #2	$19.77	8.160%	$21.3832	$21.38	$21.40	$21.40
Purchase #3	$10.34	11.502%	$11.5293	$11.53	$11.55	$11.50
Purchase #4	$67.29	8.161%	$72.7815	$72.78	$72.80	$72.80
Purchase #5	$149.61	11.413%	$166.685	$166.69	$166.70	$166.70
Purchase #6	$24.32	4.637%	$25.4477	$25.45	$25.45	$25.40
Purchase #7	$230.59	8.690%	$250.6283	$250.63	$250.65	$250.60
7 purchase totals =	$694.65		$748.6013	$748.61	$748.70	$748.50