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	$233.98	3.357%	$241.8347	$241.83	$241.85	$241.80
Purchase #2	$236.28	4.820%	$247.6687	$247.67	$247.65	$247.70
Purchase #3	$45.89	9.767%	$50.3721	$50.37	$50.35	$50.40
Purchase #4	$156.35	3.814%	$162.3132	$162.31	$162.30	$162.30
Purchase #5	$135.64	9.241%	$148.1745	$148.17	$148.15	$148.20
Purchase #6	$156.76	8.570%	$170.1943	$170.19	$170.20	$170.20
Purchase #7	$155.67	6.215%	$165.3449	$165.34	$165.35	$165.30
7 purchase totals =	$1,120.57		$1,185.9024	$1,185.88	$1,185.85	$1,185.90