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	$182.47	7.534%	$196.2173	$196.22	$196.20	$196.20
Purchase #2	$209.60	11.367%	$233.4252	$233.43	$233.45	$233.40
Purchase #3	$50.69	5.126%	$53.2884	$53.29	$53.30	$53.30
Purchase #4	$97.48	8.197%	$105.4704	$105.47	$105.45	$105.50
Purchase #5	$243.60	8.197%	$263.5679	$263.57	$263.55	$263.60
Purchase #6	$231.27	9.855%	$254.0617	$254.06	$254.05	$254.10
Purchase #7	$79.74	4.116%	$83.0221	$83.02	$83.00	$83.00
7 purchase totals =	$1,094.85		$1,189.0530	$1,189.06	$1,189.00	$1,189.10