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	$179.26	9.506%	$196.3005	$196.30	$196.30	$196.30
Purchase #2	$220.41	11.594%	$245.9643	$245.96	$245.95	$246.00
Purchase #3	$110.57	5.716%	$116.8902	$116.89	$116.90	$116.90
Purchase #4	$29.99	7.540%	$32.2512	$32.25	$32.25	$32.30
Purchase #5	$71.28	11.614%	$79.5585	$79.56	$79.55	$79.60
Purchase #6	$153.89	11.220%	$171.1565	$171.16	$171.15	$171.20
Purchase #7	$241.69	11.384%	$269.204	$269.20	$269.20	$269.20
7 purchase totals =	$1,007.09		$1,111.3252	$1,111.32	$1,111.30	$1,111.50