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	$188.58	11.192%	$209.6859	$209.69	$209.70	$209.70
Purchase #2	$188.55	11.802%	$210.8027	$210.80	$210.80	$210.80
Purchase #3	$156.46	3.833%	$162.4571	$162.46	$162.45	$162.50
Purchase #4	$41.45	7.235%	$44.4489	$44.45	$44.45	$44.40
Purchase #5	$196.76	6.192%	$208.9434	$208.94	$208.95	$208.90
Purchase #6	$106.49	7.220%	$114.1786	$114.18	$114.20	$114.20
Purchase #7	$88.83	11.784%	$99.2977	$99.30	$99.30	$99.30
7 purchase totals =	$967.12		$1,049.8143	$1,049.82	$1,049.85	$1,049.80