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	$174.54	12.793%	$196.8689	$196.87	$196.85	$196.90
Purchase #2	$165.63	7.606%	$178.2278	$178.23	$178.25	$178.20
Purchase #3	$55.57	6.401%	$59.127	$59.13	$59.15	$59.10
Purchase #4	$145.73	6.463%	$155.1485	$155.15	$155.15	$155.10
Purchase #5	$211.28	4.274%	$220.3101	$220.31	$220.30	$220.30
Purchase #6	$162.27	5.276%	$170.8314	$170.83	$170.85	$170.80
Purchase #7	$213.27	5.633%	$225.2835	$225.28	$225.30	$225.30
7 purchase totals =	$1,128.29		$1,205.7972	$1,205.80	$1,205.85	$1,205.70