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	$85.82	13.218%	$97.1637	$97.16	$97.15	$97.20
Purchase #2	$40.29	12.808%	$45.4503	$45.45	$45.45	$45.50
Purchase #3	$223.90	10.279%	$246.9147	$246.91	$246.90	$246.90
Purchase #4	$39.96	10.257%	$44.0587	$44.06	$44.05	$44.10
Purchase #5	$116.66	11.618%	$130.2136	$130.21	$130.20	$130.20
Purchase #6	$233.37	12.869%	$263.4024	$263.40	$263.40	$263.40
Purchase #7	$180.39	6.183%	$191.5435	$191.54	$191.55	$191.50
7 purchase totals =	$920.39		$1,018.7469	$1,018.73	$1,018.70	$1,018.80