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	$186.75	4.686%	$195.5011	$195.50	$195.50	$195.50
Purchase #2	$173.32	13.577%	$196.8517	$196.85	$196.85	$196.90
Purchase #3	$101.31	5.510%	$106.8922	$106.89	$106.90	$106.90
Purchase #4	$87.99	6.714%	$93.8976	$93.90	$93.90	$93.90
Purchase #5	$33.81	6.225%	$35.9147	$35.91	$35.90	$35.90
Purchase #6	$232.26	13.409%	$263.4037	$263.40	$263.40	$263.40
Purchase #7	$181.43	10.641%	$200.736	$200.74	$200.75	$200.70
7 purchase totals =	$996.87		$1,093.1970	$1,093.19	$1,093.20	$1,093.20