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	$233.77	12.813%	$263.723	$263.72	$263.70	$263.70
Purchase #2	$171.71	12.435%	$193.0621	$193.06	$193.05	$193.10
Purchase #3	$161.41	8.598%	$175.288	$175.29	$175.30	$175.30
Purchase #4	$82.64	8.254%	$89.4611	$89.46	$89.45	$89.50
Purchase #5	$10.57	5.712%	$11.1738	$11.17	$11.15	$11.20
Purchase #6	$196.61	8.550%	$213.4202	$213.42	$213.40	$213.40
Purchase #7	$162.89	11.132%	$181.0229	$181.02	$181.00	$181.00
7 purchase totals =	$1,019.60		$1,127.1511	$1,127.14	$1,127.05	$1,127.20