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	$169.35	3.842%	$175.8564	$175.86	$175.85	$175.90
Purchase #2	$18.35	13.292%	$20.7891	$20.79	$20.80	$20.80
Purchase #3	$24.47	5.612%	$25.8433	$25.84	$25.85	$25.80
Purchase #4	$77.29	7.146%	$82.8131	$82.81	$82.80	$82.80
Purchase #5	$232.39	11.491%	$259.0939	$259.09	$259.10	$259.10
Purchase #6	$119.26	6.736%	$127.2934	$127.29	$127.30	$127.30
Purchase #7	$136.94	11.320%	$152.4416	$152.44	$152.45	$152.40
7 purchase totals =	$778.05		$844.1308	$844.12	$844.15	$844.10