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	$134.49	6.819%	$143.6609	$143.66	$143.65	$143.70
Purchase #2	$211.38	3.844%	$219.5054	$219.51	$219.50	$219.50
Purchase #3	$66.66	6.384%	$70.9156	$70.92	$70.90	$70.90
Purchase #4	$232.82	3.302%	$240.5077	$240.51	$240.50	$240.50
Purchase #5	$68.69	4.430%	$71.733	$71.73	$71.75	$71.70
Purchase #6	$78.65	4.779%	$82.4087	$82.41	$82.40	$82.40
Purchase #7	$220.85	6.154%	$234.4411	$234.44	$234.45	$234.40
7 purchase totals =	$1,013.54		$1,063.1724	$1,063.18	$1,063.15	$1,063.10