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	$147.76	3.654%	$153.1592	$153.16	$153.15	$153.20
Purchase #2	$19.69	8.787%	$21.4202	$21.42	$21.40	$21.40
Purchase #3	$78.55	4.472%	$82.0628	$82.06	$82.05	$82.10
Purchase #4	$220.29	4.602%	$230.4277	$230.43	$230.45	$230.40
Purchase #5	$180.61	11.114%	$200.683	$200.68	$200.70	$200.70
Purchase #6	$218.66	11.295%	$243.3576	$243.36	$243.35	$243.40
Purchase #7	$59.35	3.360%	$61.3442	$61.34	$61.35	$61.30
7 purchase totals =	$924.91		$992.4547	$992.45	$992.45	$992.50