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	$78.92	13.245%	$89.373	$89.37	$89.35	$89.40
Purchase #2	$170.82	4.811%	$179.0382	$179.04	$179.05	$179.00
Purchase #3	$79.38	7.387%	$85.2438	$85.24	$85.25	$85.20
Purchase #4	$158.37	4.419%	$165.3684	$165.37	$165.35	$165.40
Purchase #5	$71.53	7.723%	$77.0543	$77.05	$77.05	$77.10
Purchase #6	$222.72	13.618%	$253.05	$253.05	$253.05	$253.10
Purchase #7	$189.74	3.427%	$196.2424	$196.24	$196.25	$196.20
7 purchase totals =	$971.48		$1,045.3701	$1,045.36	$1,045.35	$1,045.40