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	$178.62	9.809%	$196.1408	$196.14	$196.15	$196.10
Purchase #2	$134.29	5.456%	$141.6169	$141.62	$141.60	$141.60
Purchase #3	$172.99	7.194%	$185.4349	$185.43	$185.45	$185.40
Purchase #4	$183.26	9.539%	$200.7412	$200.74	$200.75	$200.70
Purchase #5	$92.34	3.133%	$95.233	$95.23	$95.25	$95.20
Purchase #6	$96.30	3.744%	$99.9055	$99.91	$99.90	$99.90
Purchase #7	$175.56	8.381%	$190.2737	$190.27	$190.25	$190.30
7 purchase totals =	$1,033.36		$1,109.3460	$1,109.34	$1,109.35	$1,109.20