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	$178.40	12.199%	$200.163	$200.16	$200.15	$200.20
Purchase #2	$178.58	3.783%	$185.3357	$185.34	$185.35	$185.30
Purchase #3	$233.82	5.643%	$247.0145	$247.01	$247.00	$247.00
Purchase #4	$22.95	5.849%	$24.2923	$24.29	$24.30	$24.30
Purchase #5	$182.29	7.671%	$196.2735	$196.27	$196.25	$196.30
Purchase #6	$236.46	7.628%	$254.4972	$254.50	$254.50	$254.50
Purchase #7	$39.73	3.146%	$40.9799	$40.98	$41.00	$41.00
7 purchase totals =	$1,072.23		$1,148.5561	$1,148.55	$1,148.55	$1,148.60